Water heater



Dec. 28, 1948. c. M. osTERl-nmY 2,457,597

WATER HEATER Filed NOV. 19, 1946 INVENTOR.

CLARK M. @STERHLD AWM/M Patented Dec. 28, 1948 WATER HEATER Clark M. Osterheld, Stoughton, Wis., assignor to McGraw Electric Company, Elgin, Ill., a cor-` poration of Delaware Application November 19, 1946, Serial No. 710,775

1 Claim. l

My invention relates to electric heaters and particularly to water heaters of the internal type.

An object of my invention is to provide an internal water heater of a new and improved kind.

Another object of my invention'is to provide a novel form of electric water heater in which insulation integral with the component parts thereof are provided.

Other objects of my invention will either be apparent from a description of several forms of device embodying my invention or will be set forth in the course of such description and be pointed out in the appended claim.

In the drawings,

Figure 1 is a view in vertical section through a domestic iron hot water tank having associated therewith an electric water heater embodying my invention,

Fig. 2 is a view in side elevation of my improved electric water heater with certain parts cut away to show the internal construction thereof,

Fig. 3 is a fragmentary view of a modication of electric heater embodying my invention,

Fig. 4 is a view in lateral section thereof taken on the line 4-4 of the Fig. 3, and,

Fig. 5 is a view in lateral section therethrough taken on the line 5-5 of Fig. 2.

Referring first of all to Fig. 1 of the drawings, I have there shown a standard domestic iron hot water tank comprising a lower closure I3, having associated therewith a cold water inlet pipe I5 and an upper closure member |1 having associated therewith a hot water outlet pipel9.

I provide also a mass 2| of electric insulating material which is held in proper operative position as by an outer casing 23.

I provide an internal water heater which comprises a tubular member 21 which is shown as being substantially of square shape in cross section. Within tubular member 21 I provide a plurality of liners 29, four in number, and within the four liners 29 I provide four resistance conductors 3|. Each resistance conductor comprises a plurality of transversely extending end-connected convolutions, these convolutions of strip, and while I may use a material for the conductors 3| substantially the same as is now used for resistance conductors I may also use aluminum.

I provide a terminal lead 33 for the inner end of each of the resistance conductors 3| and I provide a second terminal lead 35 for the outer end of each resistance conductor.

The wall thickness of tube 21 may be on the order of .035" in thickness although it may vary between the limits of .03" to .04, or even slightly 2 beyond these values. The thickness of the liners 29 and of additional liners 31, which liners 31 are used to space apart the individual resistance conductors 3| may be on the order of .015" and may vary between the limits of .01 to .02". The thickness of the conductor 3| and distance between adjacent convolutions may be determined by the amount of energy to be translated into heat in a heater of this kind yand also by the length of the heater 25.

The entire outer surface of resistance conductor 3| is covered by an integral, inorganic, heat-conducting, high-temperature-resisting and electric-insulating coating having a thickness of the order of .001l although I desire it to be understood that the thickness of this coating may vary between the limits of .0005 and .0015". U. S. Patent #1,526,127 discloses one process for making such a coating. The liners 29 and 31 may have a thickness on the order of .015" and be also covered by a coating of the same kind and thickness as hereinbefore described for the resistance conductor 3|.

vThe heater 25 is held in proper operative position and watertight engagement with tank by a member 39 and by a washer 4|, which washer 4| is provided with an inward extension 43 adapted to engage a washer of electric insulating material. A pair of bolts 45 with nuts 41 thereon hold the heater assembly in watertight engagement with tank Member 39 is secured to the outer face of tank by a welded seam.

I provide a plurality of sheaths 49 on the casing 21, these sheaths 49 being preferably of relatively thin aluminum, the thickness of this aluminum being variable between the limits of .015" to .035". Each sheath 49 is substantially channel shape in lateral section, with side portions 5| whereby it may be secured against the outer surface of one of the sides of tube 21 so that it may conduct heat from the resistors 3| to the water in the tank I Referring now to Figs. 3 and 4 of the drawings, I have there shown a modiiication of an electric heater embodying my invention. this electric heater comprising a tube 55 which may be made of circular shape in cross section and which has positioned therein a liner 51 preferably of aluminum. The tube 55 may also be made of aluminum. Within tube 55 and liner 51 I position a resistance conductor 59 which comprises a strip of resistance material which is wound on edge in substantially helical form and which when placed in proper operative position within tube 55 will hold liner 51 tightly against the inner sur- 3 face of tube 55. The resistance conductor is preferably made of aluminum.

I provide a plurality of sheaths 5l which are preferably made `of aluminum which is relatively thin, the wall thickness of sheath `6| being on the order of .015'l to .035. Each of the hollow `sheaths 6I is provided with side portions 63 which lare adapted to be tightly secured against the outer surface of tube 55 so as to conduct heat generated within tube 55 away from the tube `and into the water in tank I l.

The device embodying my invention thus provides a novel form of electric water heater which will not be too great to enable it to be installed in a .tank Il through a relatively small opening. The use of an integral, inorganic, electric-insulating coating,T of the relatively small thickness hereinbelore mentioned permits of making the heater of minimum dimension-s and still `obtain a relatively large amount of heat generated therein.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire that all such modieations clearly coming within the scope of the appended claim shall be consldered a part of my invention.

I claim as my invention:

An electric water heater for insertion into a hot water tank, comprising ya relatively thin,

4 round, tubular, metallic casing having closed inner end, a thin metal liner covering substantially :all of the inner surface of said casing, a metallic resistor strip helically Wound on edge ln said casing and inherently expanded to hold said liner in tight engagement with said casing and a heat-transmitting sheath on said casing forming with the external surface of said casing a series `oi longitudinal spaces, the inner surface of said casing, the entire surface of said liner and of said resistor strip having thereon an integral, inorganic, heat-conducting, hightemperaturere sisting and electric-insulating coating.

CLARK M. OSTERHELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,117,240 Presser Nov. 17, 1914 1,667,257 Hicks et 21.1 Api. 24, 1928 1,669,385 Wiegand et al May 8, 1928 1,699,542 Murray Jan, 22, 1929 1,389,445 Lightfoot Nov. 29, 1932 1,996,625 Eendleton Apr. 2, 1935 2,310,325 Smith Feb. 9, 1943 2,357,906 Osterheld Sept. 12, 1944 

